The present invention is directed to a suspension hanger having an adjustment cam which provides limited horizontal adjustment for alignment of an axle relative to a vehicle chassis.
The present invention relates to an adjustable suspension hanger, which allows limited adjustment, within the horizontal plane, for alignment of the vehicle axle in relation to the vehicle chassis, a control arm and axle attachment assembly, which facilitates ease of adjustment, removal and replacement of the axle.
A common reoccurring problem in vehicle suspension systems is misalignment of the axle in relation to the vehicle chassis. Such misalignment contributes to increased tire and axle component wear. Further, significant misalignment can adversely impact the steerability of the vehicle potentially resulting in lost control.
The known methods and systems for vehicle suspension alignment, particularly heavy truck and trailer suspensions, generally involve lengthy and complex manipulation or adjustment of the suspension itself or require welding, drilling, or additional fastening of suspension components. It is not uncommon, on heavy-duty suspensions, to eliminate undesirable axle travel or misalignment, by welding the control arm fastener to the hanger bracket once alignment is achieved. Some manufacturers choose not to provide any alignment adjustment at the hanger bracket but rather rely on achieving permanent alignment at the time of manufacture. On many systems it is necessary to remove all, or a portion of the axle assembly to replace or add parts to ensure appropriate alignment. Preferably, the alignment operation is performed without removing any components or parts from the vehicle and should be convenient and inexpensive.
Particular problems exist in alignment of heavy-duty axles or suspension systems utilized in commercial, high load, vehicles. Unlike passenger vehicles, commercial vehicles generally have heavy-duty axles and suspensions which are difficult to maneuver or adjust and are generally expensive to repair. Any alignment system which requires welding, removal of components, replacement of components, or suspension disassembly is undesirable. Common axle alignment methods often require partial disassembly of the suspension mechanism, particularly at the hanger, and require the insertion or extraction of shims between the control arm bush and the hanger bracket.
It is also common to find large eccentric bores formed through the vehicle hanger bracket which, when the control arm pin is fitted with large washers or cams, allow significant movement of the control arm bush within the hanger bracket. While only horizontal displacement of the axle relative to the vehicle chassis is desirable during the alignment process, it is common to experience vertical displacement of the axle with known systems utilizing a large eccentric bore and compression bolts, or similar fasteners, to facilitate alignment.
Alignment of these relatively simple systems typically requires loosening the bush pin, or compression bolt, and manipulating the control arm within the confines of the bore provided through the hanger. When the desired positioning is acquired, the fastener is secured and will generally retain the control arm position within the hanger. However, any undesirable vertical movement of the control arm and attached axle relative to the vehicle chassis imparts uneven force on the vehicle frame, which results in vertical frame misalignment.
Moreover, most alignment methods often require significant trial and error to find the desired alignment as they lack means for manipulating the control arm within the bracket. A typical method for aligning would include raising the vehicle from the ground, loosening the control arm bush pin and applying significant horizontal force to the vehicle axle, such as with a ram or hammer.
At this time, there are no known suspension assemblies which allow easy and inexpensive horizontal alignment of heavy duty, commercial grade, axles. It is therefore desirable to provide an axle alignment system which is easy to operate, which eliminates vertical displacement of the axle during alignment and which does not require any disassembly or replacement of parts. It is also desirable to provide a heavy-duty axle alignment system which eliminates welding. Further, it is desirable to provide an axle alignment system which, when positioned and correctly fastened, eliminates unwanted movement which results in misalignment.
The present invention addresses the above described problems and limitations standard in the art by providing a suspension hanger mechanism which allows easy, inexpensive and secure horizontal alignment of the vehicle axle relative to the vehicle chassis. A specially formed cam mounted to the suspension hanger bracket allows limited horizontal adjustment of the control arm bush within the hanger bracket assembly. A series of uniquely designed spaced-apart bores within the hanger bracket and the cam eliminate undesirable vertical displacement during the alignment process. Further, multiple fastening points through the hanger bracket and cam limit unintentional displacement of the axle during use.
The present invention addresses the above described problem and limitations standard in the art by providing a suspension hanger mechanism which utilizes a specially formed cam mounted to the suspension hanger bracket to facilitate easy adjustment of the control arm bush within the hanger bracket assembly. The adjustment system provides a series of uniquely designed spaced-apart bores within the hanger bracket and the cam to allow alignment without suspension disassembly and to eliminate undesirable vertical displacement during the alignment process.
A suspension hanger bracket is fixed in a typical downward orientation to a vehicle cross member or chassis. The hanger bracket has opposing sides configured to receive the bush end of a suspension control arm. Substantially near the lower edge of each hanger bracket side, a plurality of bores are provided. The bores include, starting at the top, a horizontally elongated bush pin bore and a fastener bore. The bores of each hanger side are in axial alignment with the bores of the opposing side. A bush end of a suspension control arm is received between the opposed sides of the hanger bracket, orientated so that the horizontally elongated bush pin bore is in axial alignment with the pin hole in the control arm bush. To reduce the possible deformation of the hanger bracket sides, it is preferable to install a reinforcement plate on each hanger bracket side over the series of bores. It is preferable that the reinforcement plate be of hardened steel and it must be provided with a spindle bore along with a horizontally elongated pin bore and fastening bore of the same size and orientation as those described in the bracket side.
A specially shaped cam facilitates fore and aft adjustment of the suspension control arm within the hanger bracket. The cam, preferably spade shaped, is provided with a series of openings commensurate with the hanger bracket and reinforcement plate bores. The cam has a spindle opening, a bush pin opening and an arcuate-shaped fastener opening.
A cam is positioned on the outside face of both opposed hanger bracket sides so that the series of cam openings are aligned with the series of bracket and reinforcement plate bores. Prior to positioning the control arm bush in the hanger bracket, short fasteners, preferably hardened carriage bolts, are fitted from inside the hanger brackets through the reinforcement plate fastener bore and the arcuate shaped fastening opening within the cam. It is preferred that the fastener bore of the reinforcement plate is square to prevent turning of the carriage bolt once it is in place. Use of the reinforcement plate allows the carriage bolt head to be recessed into the hanger bracket side to avoid contact between the bolt and the control arm bush.
The bush end of the control arm is positioned between the opposed bracket sides and a bush fastener is fitted through the bush pin opening through the cam and the horizontally elongated bush pin bores of the opposed bracket sides and reinforcement plates. A short spindle is movably positioned within the spindle opening of each cam into the spindle bore of the reinforcement plate. The spindle may be welded or preformed onto the cam.
A square opening is formed in the cam, substantially adjacent the fastening opening. When the bush pin and the fastening bolt are loosened, the control arm bush can be manipulated horizontally within the hanger bracket by applying force to the square opening with a breaker bar. The cam moves in an eccentric circuit due to the arcuate-shaped fastener opening. The cam moves about the fastening bolt which is retained within the fastening bore of the reinforcement plate. The bush pin opening of the hanger bracket prevents vertical displacement of the bush pin relative to the hanger while allowing horizontal displacement of the bush pin within the horizontally elongated bush pin bore in the hanger bracket sides. The spindle provides a pivot about which the. cam moves. The arcuate-shaped fastener opening compensates for, and eliminates vertical displacement, by allowing the cam to travel an eccentric circuit while maintaining the bush pin within a horizontal plane defined by the horizontally elongated bush pin bore the hanger bracket.
When the desired alignment of the axle is achieved, determined by the control arm bush orientation within the hanger bracket, the bush pin and fastening bolts are tightened. The fastener bolts and bush pin provide two distinct compression points which secures the control arm bush relative to the bracket and greatly reduces the potential for undesired displacement during vehicle operation.
When the axle is aligned and the bush pin and fastening bolts are secured, significant pressure should be exerted to maintain control arm bush positioning. The suspension hanger is also provided with an upper shock absorber bracket, preferably on the inboard side, substantially near the mounting plate.
As the control arm is fixed to the axle any change in relation between the bush end of the control arm in the suspension bracket results in linear forward or rearward movement of that axle with respect to the vehicle chassis.
Each suspension system requires two opposed hanger brackets positioned on either side of the vehicle chassis. It is understood that the disclosure herein specifically describes a single hanger bracket and the second hanger bracket would be a mirror image of the first.